Melt the chocolate in a heatproof bowl over a saucepan of simmering water to melt – the chocolate must not overheat.
Whisk the egg whites in a separate bowl until they form soft peaks; stir the liqueur into the beaten egg yolks and add this to the melted chocolate.
Now pour the chocolate/egg mixture into the egg whites and gently fold together; divide evenly between four ramekins and place in the fridge to chill – serve with whipped cream and decorate as you wish.